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Re: Oxygen sensor - part number??

Go with 234-1056. I double checked and cross referenced and it appears that Denso changed that part number.

FWIW, I looked up the Toyota part number to be 89465-29195, then cross referenced it on Denso's website. I checked the old part number of 234-1051 but according to Denso that part number doesn't exist anymore. When I type that number into www.sparkplugs.com's cross reference system it still comes up as a valid part number, so if they still have those I'm pretty sure they would work too. Tim

PS: to avoid future confusion I changed my original post to reflect the current part number.

Re: Oxygen sensor - part number??

Yeah, this is an old thread. Even older than the date here suggests (as I copy/pasted it from one of my posts over at TVP). As these things get older sometimes parts like this go down Yeah! Of course this is off-set more & more as things become NLA & dealer parts (whatever they have left) continue to go up.

Re: Oxygen sensor - part number??

Just a quick update for anyone looking to replace their O2 sensors. I recently placed an order through Amazon for Denso upstream and downstream sensors. I did OEM replacement for the upstream (Denso 234-4055) and universal replacement for the downstream (Denso 234-2050). The reason behind mix and matching OEM w/ universal was because Amazon gave me a screaming deal on the pair, $51.00 prime shipping for both, did I mention that they're (supposed to be) DENSO?!?!?!?Anyways, get the package and tear them open, the OEM upstream replacement is as advertised (albeit it the sensor itself looked slightly different) and goes right in no problem. After hours of drinking and fighting with removing the nuts for the downstream sensor, which were horribly rusted and rounded, I open up the Denso downstream sensor box, and there's a Bosch sensor in there! Feeling like I just got slapped with a trout, I immediately pull up Amazon and see the following line on their product information page:

Note: Denso partners with other manufacturers to supply the parts your car was originally built with. This product is in a Denso package, however the part may have been manufactured by an independent Denso supplier.

So, unless I really got shafted by someone at the Amazon warehouse, apparently Denso is selling other manufacturer's sensors as their own. The Bosch sensor came in a Denso box and all the numbers on the box matched up with my order. I'm sort of left in quandary because I'm honestly not sure the hassle of returning the Bosch sensor is worth it, especially since it is brand new and AFAIK, will still work. I know some people do not like to put Bosch parts on their Toyotas but I'm not sure why.

I'm not sure if this is an Amazon only thing but I wanted to put it out there so other TVT guys are aware. The Bosch sensor appears to be high quality and I really only looked into it because the sensor is distinctly different looking from the Denso ones. Reading the size 1 font etched onto the sensors was the only other giveaway.

Re: Oxygen sensor - part number??

Yeah, I'm a little hesitant towards Bosch, but I don't actually have good reason to be (at least not on their o2 sensors). I got an o2 sensor code on my 86 & fuel economy went in the toilet so I swapped it out with a new Bosch universal sensor. 2 weeks later I got the same code again (not to mention I continued getting crappy gas mileage). This time I put in a Denso, but as a precaution I also ran a new wire from the sensor up to the ECU. No more codes and fuel economy instantly improved (about 40%). I know when troubleshooting you're only supposed to change one thing at a time, but I was impatient and wanted the problem gone.

So anyway, the question is "did the Denso sensor solve the problem or was it the new wire?". I guess I'll never know, but since then I've been prejudiced against the Bosch sensors. Tim

Re: Oxygen sensor - part number??

Just ordered and received o2 sensors off sparkplugs.com , for my 88 LE 4wd. Wanted to double check I ordered correctly? As the new sensors are a little smaller than the old ones pulled out. Actually I'm only comparing the upstream sensor at the moment as the rear downstream sensor nuts are rusted and rounded and i'm stuck trying to get them off.. ug.

Re: Oxygen sensor - part number??

Going bonkers. Cursing and hacking I finally got the rusted stripped nut off the rear o2 sensor bolt.. took some work but the sensor finally came out. Go to slip the new one in and it doesn't fit. The one upstream fit fine... I'm about to just cut the rear tail pipe off I've had it ...do i even need the downstream o2 sensor? ha.....

perhaps the downstream sensor mount is not original? Not sure what to do.. Maybe drill out the hole in the mount to fit new sensor? hmmmm

Re: Oxygen sensor - part number??

Originally Posted by ratatouille

the new sensors are a little smaller than the old ones pulled out.

That was my experience with the upstream sensor as well when comparing it to the (I assume original) one that came off of the van. I just chalked it up to minor improvements made in the past 26+ years. My new upstream is working fine and throwing no codes so I wouldn't worry about the minor changes.

Originally Posted by ratatouille

Going bonkers. Cursing and hacking I finally got the rusted stripped nut off the rear o2 sensor bolt.. took some work but the sensor finally came out. Go to slip the new one in and it doesn't fit.

That sounds like me last month with the cursing and hacking . That is strange that the new sensor doesn't fit, maybe there is residual gasket material/junk on the edges of the hole that is blocking installation of the new one? I don't imagine that's the case though (worth a shot). I don't see how drilling out the hole would hurt but getting a drill to it might be hard with all the angles and where it's located.

Re: Oxygen sensor - part number??

Yeah at first I thought it might be gunked up.. but its not. It definitely does not fit. It is a little tight to get a drill in there to try and drill out the hole. Kinda stumped at this point. I may need to find a different sensor that will fit.

Upon closer inspection of the old removed ones, they are marked as Toyota sensors. Which makes me think the rear mounting is original and not modified...

Re: Oxygen sensor - part number??

Was able to drill out hole a little larger to fit the sensor. How important is it to a have a good seal between exhaust mount, gasket and sensor flange? After tightened down it looks like there is a little bit of gap between. I was afraid to tighten too much for risk of breaking the already abused mounting bolt...

Re: Oxygen sensor - part number??

Originally Posted by ratatouille

Was able to drill out hole a little larger to fit the sensor. How important is it to a have a good seal between exhaust mount, gasket and sensor flange? After tightened down it looks like there is a little bit of gap between. I was afraid to tighten too much for risk of breaking the already abused mounting bolt...

I would imagine that its fairly important. If there is not a good seal between all parts the van will likely sound a little worse, as its essentially an exhaust leak. Outside air getting into the area might mess with the voltage that the downstream sensor reads as well. It obviously doesn't need to be torqued down, but hopefully you can get enough on the bolts so that it makes a nice tight seal.

Re: Oxygen sensor - part number??

I'm going through a similar saga with the nuts on oxygen sensors being rusted and rounded. The downstream sensor is definitely the worst, but both are bad enough that a socket won't fit on them and there is just not room there to get most of my tools in! What ended up working for you guys? Any tips or tricks. I don't know if all vans have these splash guard things on them but they make the whole situation pretty tight.

I (maybe stupidly) tried to cut into one of the nuts on the downstream sensor because I thought it might be rusted enough to just break open easily. It hasn't yet though. May not be using the right tool (Dremel) and can't really get to the nut from another angle with this.

Ready to go crazy so any help would be much appreciated!

The last picture isn't an oxygen sensor obviously but something I saw while down there above the oil pan and was wondering what it was if anybody knows.

Re: Oxygen sensor - part number??

I ended up cutting out that shield as I couldn't get any access either. I figured a new shield would be easy enough to fab with some scrap metal if need be, but am not running any kind of shield as I live in the southwest and it rarely rains. I suppose the shield would also block rocks and other debris, but

Once I cut out the shield I had plenty of access but the nuts were all rusted to hell. It still took a few more hours of PBlaster, yelling, cursing, and a pair of vice grips before I could get the bolts free.

As for that last picture, I believe that's the rear transmission mount (see below)

Thanks for pointing this out, I went out to look at mine after looking at this thread and the whole bottom half of the mount has eroded away to nothing, like I could stick my finger in it and slide it around the whole bottom half of the mount, which I'm pretty sure isn't right or safe. I'll be tackling this imminently once I finish my current project (rebuilding the drums ).

Re: Oxygen sensor - part number??

Just a heads up that I also had to bore out the rear O2 sensor hole of my '88 4wd to allow the new sensor to fit (Denso #234-2062. ​Wasn't a huge deal, but it didn't plug right in.

For anybody else doing this, Toyota used 2 different rear sensors in 1988, but now both are obsolete and cross-over to a single part number (Toyota #89465-29336). That part number is supplied to Toyota by Denso (Denso #234-2062), so if you're after OE (in my opinion the best), and don't want to pay extra for the little red box that says "Toyota" on it, then this is the one you want. It is specifically for 88 - 89 vans and will work in the rear sensor location only. And yes, on some vans you will likely need to bore out the hole a bit (I know it's a PITA). It's possible some aftermarket sensors will fit without the mod, but I couldn't say which ones and/or the quality you could expect. Tim